地球物理学进展 ›› 2019, Vol. 34 ›› Issue (1): 354-364.doi: 10.6038/pg2019BB0569

• 应用地球物理学Ⅱ(海洋、工程、环境、仪器等) • 上一篇    下一篇

裂隙充填型天然气水合物储层的各向异性饱和度新估算及其裂隙定量评价

钱进1,2,3,王秀娟1,2,3,董冬冬1,3,4,SAINKalachand5,叶月明6   

  1. 1. 中国科学院海洋研究所,海洋地质与环境重点实验室, 山东青岛 266071
    2. 青岛海洋科学与技术国家实验室,海洋矿产资源评价与探测技术功能实验室, 山东青岛 266071
    3. 中国科学院海洋大科学研究中心, 山东青岛 266071
    4. 青岛海洋科学与技术国家实验室,海洋地质过程与环境功能实验室, 山东青岛 266061
    5. 印度国家地球物理研究所, 海德拉巴 500007,印度
    6. 中国石油杭州地质研究院, 杭州 310023
  • 收稿日期:2018-04-13 修回日期:2018-10-25 出版日期:2019-02-20 发布日期:2019-04-15
  • 作者简介:钱进, 男, 1982年生, 汉族, 江苏姜堰人, 博士, 副研究员, 主要从事海洋定量地震解释以及正演数值模拟方面的研究工作.(E-mail: qianjin@qdio.ac.cn)
  • 基金资助:
    国家自然科学基金项目(41676040);国家自然科学基金项目(41676041);国家自然科学基金项目(41504105);国家重点研发计划(2017YFC0307601);国际科技合作计划联合资助.(2010DFA21740)

New estimation of anisotropic saturation and fracture quantitative evaluation for fracture-filling gas hydrate reservoir

QIAN Jin1,2,3,WANG Xiu-Juan1,2,3,DONG Dong-dong1,3,4,SAIN Kalachand5,YE Yue-ming6   

  1. 1. Key Laboratory of Marine Geology and Environment and Institute of Oceanology, Chinese Academy of Sciences, Shandong Qingdao 266071, China
    2. Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Shandong Qingdao 266071, China
    3. Center for Ocean Mega-Science, Chinese Academy of Sciences, Shandong Qingdao 266071, China
    4. Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Shandong Qingdao 266061, China
    5. CSIR-National Geophysical Research Institute, Hyderabad 500007, India
    6. Hangzhou Research Institute of Geology, PetroChina, Hangzhou 310023, China
  • Received:2018-04-13 Revised:2018-10-25 Online:2019-02-20 Published:2019-04-15

摘要:

天然气水合物有时会以结核状、层状、脉状或块状等裂隙形态发育在深水盆地的细粒泥质沉积物中, 该类型天然气水合物被称为裂隙充填型. 与孔隙充填型不同, 裂隙充填型天然气水合物储层由于裂隙的出现, 在测井速度、电阻率和地震数据上会呈现明显的各向异性特征. 本文利用细层层状介质模型和有效介质理论(EMT)新估算出印度克里希纳—戈达瓦里(K-G)盆地NGHP-01-10A和10D孔裂隙充填型水合物储层的各向异性饱和度, 纵波(Vp)和垂直极化横波(Vsv)测井速度估算的平均饱和约为20%, 明显优于水平极化横波(Vsh)估算结果, 且与压力取心估算结果更为一致. 倾角随深度变化曲线和不同角度估算的水合物饱和度结果都表明10A孔浅部以高倾角裂隙为主, 深部出现低倾角裂隙;10D孔以垂直裂隙为主, 这说明两口相距10 m的孔中裂隙在空间上延伸长度较小;而10B-08Y岩心的X射线成像定量评价结果显示水平裂隙倾角位于0°~21°, 高倾角裂隙倾角位于68°~89°, 裂隙尺度为厘米级, 最大高度、宽度和纵横比分别为27.66 cm、6.71 cm和170. 此外, 水合物饱和度估算的影响因素分析表明, 地层岩性和方程计算参数对饱和度估算的准确与否至关重要, 与简化三相方程相比, 有效介质理论计算参数的物理意义明确, 参数选择简易, 因此计算也更为准确与便捷.

关键词: 裂隙充填型天然气水合物, 有效介质理论, 裂隙定量评价, 各向异性, 饱和度

Abstract:

In the deepwater basin, gas hydrates are sometimes developed in the form of nodular, veins, layers or massive of pure gas hydrate within the fine-grained sediments, which we called fracture-filling gas hydrate. Fracture-filling gas hydrate is distinguished from pore-filling gas hydrate because velocity, resistivity and seismic data always appear to be anisotropy in the fractured reservoir. Based on the layered medium model, the effective medium theory was used to newly estimate anisotropic saturation in the fracture-filling gas hydrate reservoir for the two holes of NGHP-01-10A and -10D, Krishna-Godavari Basin, India. The average anisotropic hydrate saturations estimated from P-wave velocity and vertical polarized S-wave velocity are consistent with those estimated from pressures cores with the value of 20%. Dip curve and anisotropic saturations show that fractures in shallow sediments has remained predominantly with high angles and fractures with small angles appear in deep sediments while only vertical fractures exist in the hole 10D, which illustrates the extent of gas hydrate filled fractures is short between the two holes with 10 m apart. X-ray image shows the dip of fractures with centimeter scale are concentrated at 0° to 21° and 68° to 89° and the maximum height, width, and aspect ratio of fractures are 27.66 cm, 6.71 cm, and 170, respectively. In addition, the analysis of influencing factors shows that both sediment lithology and calculation parameters of equation are very important to accurately estimate the gas hydrate saturation. Compared with the three-phase simplified equation, the calculation of effective medium theory is more accurate and convenient because of its explicit physical meaning and simple calculation parameters.

Key words: Fracture-filling gas hydrate, Effective medium theory, Fracture quantitative evaluation, Anisotropy, Saturation

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